In comparison with Long Term Evolution (LTE), a higher carrier frequency such as 38 GHz or 72 GHz is used in a 5G communications system, to implement wireless communication with a larger bandwidth and a higher transmission rate. Because a carrier frequency is relatively high, a radio signal transmitted by using the carrier frequency encounters more severe fading in a spatial propagation process, and even it is difficult to detect the radio signal at a receive end. Therefore, a beamforming technology is to be used in the 5G communications system to obtain a beam with good directivity, to increase power in a transmit direction and improve a signal to interference plus noise ratio (SINR) at the receive end. To improve communication quality, the beamforming technology is also used on a user equipment (UE) side to generate analog beams in different directions for receiving and sending data. Because a base station and user equipment communicate with each other by using a relatively narrow analog beam, better communication quality can be obtained only when the analog beams for sending and receiving are aligned. Therefore, it has been determined in the 3GPP RAN1 meeting that a beam sweeping process is used in New Radio (NR) to determine a beam pair between the base station and the UE, and a plurality of beam pairs are monitored in a communication process, to improve robustness of a communication link.
Further, to extend coverage of a network device and ensure that a terminal device can quickly obtain a synchronization signal, system information, and the like required for accessing a network, the information needs to periodically broadcast in NR. In NR, a synchronization signal block (SS block) includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and/or a new radio physical broadcast channel (NR-PBCH), and the SS block may occupy a plurality of orthogonal frequency division multiplexing (OFDM) symbols that are related to a carrier band and a subcarrier spacing. FIG. 1 is a schematic structural diagram of an SS burst set according to this application. One or more SS blocks form one synchronization signal burst SS burst, and one or more SS bursts form one synchronization signal burst set SS burst set.
However, in an actual communication process, the network device may need to configure different quantities of SS blocks in an SS burst set based on different service requirements. Therefore, how the network device effectively notifies the terminal device of a quantity of SS blocks is a problem that needs to be urgently resolved.